Safety device for motion picture projecting machines



Aug. 23, 1932. J. E. COHEN 1,873,738

- SAFETY DEVICE FOR MOTION PICTURE PROJECTING ncmuss Filed July 9. 1927 5 Sheets-Sheet l W WITNESSES:

INVENTOR.

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Aug. 23, 1932.

J. E. COHEN 1,873,738 SAFETY DEVICBJFOR MOTION PICTURE PROJECTI NG IACHINES v Filed July 9. 1927 5 Sheets-Sheet 2 LIZ Hi i WHAESsES: INVENTOR:

Aug. 23, 1932.

J. E. COHEN 1,873,738 SAFETY DEVICE FOR IOTION PICTURE PROJECTING IACHINES Filed July 9. 1927 5 Sha ts-Sheet 3 TIC 6 I'I(? 9 w W f; I 22 4 w 41 j J! WITNESSES: ZIALVEIYTOR osqpfi liaswhen,

8- 23, 1932- T J. E. COHEN I 1,873,738

SAFETY DEVICE FOR MOTION PICTURE PROJECTING IACHINBS Filed July 9. 1927 5 Shoots-Sheet 4 INVENTOR:

Aug. 23, 1932. E, HEN 1,873,738

SAFETY DEVICE FOR MOTION PICTURE PROJECTING IACHINES Filed July 9. 1927 5 Sheets-Sheet 5 1" J0 A j A 12 o 1.1 0 a [2 z W Z I 41 7}, l )M 1 1 J0 m L J J L A F m O I a 60- g l o o 0 0 5 69 .472 o M 5 I WITNE-SSBS: E N

(5 Jaisqo/zE/lzs may, I I B J M I ATTORNEY particular] Patented Aug. 23, 1932 UNITED STATES JOSEPH ELLIS COHEN, OI PHILADELPHIA,

PATENT orrlca I PENNSYLVANIA, ABSilGNOB- '10 BENTBY SAFETY CONTROL CORPORATION, OF PENNSYLVANIA mm DEVICE IOB IOTION PIUI'URE PROJECTING CHIN Application w m a, 1027. sem No. 204,454.

omitted and the housing of the attachment My invention relates to safety devices for motion picture projecting machines and more to a device which permits a dowser to all by gravity into light obstructing position; and to break the motor circuit in case the film should break, clog or tear, or in case any belt of the driving mechanism breaks or the motor. current becomes excessive or fails.

The object of my invention is to provide means, for actuating such a safety device iii case of defective operation as enumerated above.

According to. the invention the safety means comprises, in combination with means for holding the dowser out of light obstructing position, an electro-ma net normally energized and which, when eenergized by defective operation of the film across the aperture, operates to trip the means to ermit the dowser to fall by gravity into light obstructing position.

The drawings illustrate embodiments of the invention and the views therein are as follows:

Figure 1 is a side view of a preferred embodiment of my invention showing same attached to a safety device which is shown mounted upon a fragment of a projector cone; the housing of the attachment being broken open in order to expose the contents thereof.

Figures 2 and 3 are, respectively detail views of a sleeve and plun er which form parts of the device shown in igure 1.

Figure 4-is a view similar to Figure 1 but showing a modified form of m invention; one of the magnet coils being broken open in order to expose the core and plunger therein, and

Figure 5 is a detail view of a modified form of armature adapted to be used in the attachment shown in Figure 4.

Figure 6 is a view similar to Figure 1 but showing'still another modification of my invention', and I Figure 7 a rear view of the safety device shown in Figures 1, 4 and 6, to which is attached one of the several forms of my invention; the cover of the safety device being No. 172,294. This latch has a being broken en in order to expose the contents thereof Figure 8' is a sectional view of the com plete electro-magnet housing, taken on a '66 planei indicated by the line 8-8 of Figure Figure 9 a fragmentary sectional view taken on line 99 on Figure 7; the dowser handle being omitted.

Figure .10 is a wiring diagram showing the relation between my invention and the various units which comprise a complete fire preventing apparatus.

eferring now more particularly to Fig 66 ures 1, 4, 6 and 7, in whichvmy invention is shown attached to a safety device 9 having a casin 1O rovided with a base 11 by means 0 whic it may be secured to the cone 12 of a projecting machine lam housing. I0 The rear side of casinglO is c osed by a cover 13 and a shaft 14 and is journaled therein and in the front of casing 10. An electro-rnagnet 15, ada ted to be energized whenever the film brea ks, is secured to the it inside of casing 10. A mercury switch 16 is mounted on a spring bearing 17 which has its free end supported against the spring action of the bearing b a cam 18 secured to shaft 14. A dowser andle 19 is 39 fixed to the outer end of shaft 14 and carries a dowser plate 20 which is adapted to be swung between the lamp housing and the film passing through the projector in case the film should cease to move from any cause.

Dowser plate 20 is held out of light obstructing position by a latch 21, as shown in detail in the co-pending a plication of Feeney et al., filed March 3r 1927, Serial trip arm 22 formed integral therewith and its outer end extends outside of the casing 10. An armature 23 is hinged to casing just below magnet and has a bifurcated end engaging a screw inserted in the side of latch 21, so that magnet 15, when energized, will attract armature '23 and trip latch 21 and allow dowser to fall into light obstructing position.

in P

As dowser plate swings downwardly, cam 18 is rotated so that its flat face is uppermost and the free end of spring bearing 17 is thus allowed to move downwardly an tilt mercury switch 16 so that the mercury contained in the switch moves away from the switch points and opens the circuit at this point; mercury switch 16 being so con nected that the breaking of the circuit at this point will cause the stoppingeof the motor, as will hereinafter be descri d. As shown in Figure 7, I provide four binding posts in the upper part of casing 10 of whic the two outer ones are connected to the two terminals of switch 16 and the two center ones to opposite ends of the winding of electro-magnet 15.

In order to actuate safety device 9 and cause dowser 20 to intercept the rays of li ht assing through the film in case the lm should cease to move due to the breaking of a belt-or failure of power to the motor, I

provide an attachment 24 which preferably includes a housing 25 attached to casing 10. In Figure 1, I have shown housing 25 enclosing a solenoid which consists of an electro-magnet 26, a sleeve 27, a plunger 28 and g a magnet frame 29.

I suitable manner, has a lever 38 pivoted to its fall by gravity and head 36 Sleeve 27 extends upwardly through the bottoms of housing 25 and frame 29 and fits in the center of magnet 26. It is provided with a slit 30, which tends to prevent eddy currents being set up when magnet 26 is energized, and with a flange 31 through which screws 32 may be passed and threaded into the bottom of frame 29 for securing the solenoid in casing 25. Plunger 28. preferably consists of an armature 33, made 0 magnetic material and laminated or provided with a slot 34, a stem 35 of non-magnetic material, and a head 36.

A support 37, secured to casing 10 in any lower end and engages the underside of head 36 by its one end and engages the lower end of the trip arm 22 by its other end. When the magnet 26 is energized, armature 33 will be drawn into the same and the head 36 will assume the position shown in Fig. 1, but, when the magnet is deenergized, plunger 28 will will pull the end of the lever 38 downwardly and cause the opsite end to raise trip arm 22, thus permit ting the dowser 20 to fall by gravity into a light obstructing position.

In Figures 4, a fication-having a housing 25 which is quite similar to housing 25 and provided with a rib 39 to which the core 40 of an electromagnet 41 may be attached by means of screws or bolts. Core 40 is bifurcated to form a core part 42, which extends but part way through its coil, and a core part 43, which extends above its coil. A suppo the bottom of housing 25, extends upwardly nd 8, I have shown a modirt 44 is secured to along oneside of magnet 41, and has a magnet armature 45 hinged to its upper end and abutting the under side of trip arm 22.

Armature 45 is adapted to be moved upwardly by means of a sprin which may be of any desired typebut has Eeen shown as a bent spring 46 havin one end coiled about a pin 47, by means 0 which armature 45 is hinged to support 44, and having its outer end engaging armature 45, as by contacting with a screw or other projection extending from the side of the armature. When magnet 41 is energized, core part 43 will attract armature 45 and core part 42 will attract a plunger 48 hinged to armature 45. When ractical, the several parts should be carefu y machined and assembled so that the top of core part 43 will abut the underside of armature 45 and the top of core part 42 abut the bottom of plunger 48 in order to eliminate any daner of the magnet heating or the armature chattering; it being understood that the attachment should be made as small and compact as possible.

As long as ma et 41 is energized, it is evident that it will old armature 45 against the action of spring 46 but, as soon as it is deenergized', spring 46 will swing armature 45 upwardly and raise trip arm 22, releasing dowser plate 20 to permit it to fall by gravity into light obstructing position. In order that spring 46 may not swing armature 45 beyond a certain point, I provide a stop 49 secured to the side of casing 10 and adapted to limit the upward movement of the lever so that it does not move outside the field of attraction of magnet 41.

Instead of hinging plunger 48 to armature 45, as shown in Fi re 4, I sometimes em loy an armature 45 w 'ch has a plunger 48 xed rigidly thereto or formed integral therewith, as shown in Figure 5.. This armature is employed and functions in the same way as does armature 45 and plunger 48 but, in order that plunger 48 may reciprocate in the bore of magnet 41, it is necessary to slightly taper the'jorward side of its lower end.

In Figure 6, I have shown a vdevice very similar to that shown in Figure 4 and having a number of like parts which have been designated by likereference numerals, while the parts which are similar to those in Figure 4 have been designated by the same numer'als to which the exponent a has been added. In'this modification, the core 42 of a plain electro-magnet 41 is provided with two core parts 43 which are adapted to abut the bottom of armature 45 and, when the magnet is energized, hold same against the action of spring 46. The function and operation of this modification are the same as those of the modification shown in Figure 4 and, is in the former case, the parts should be so carefully made and assembled that the apparatus is shown, 50

' throu h 65 an 66 respectively. 1 Roller 65 is rotatd long as switches 50, 16 and 60 are closed, a curava-no tops of both core parts 43 abut the underside of armature 45.

Referring now to Figure 10, in which a method of wiring a complete fire. prevntin represents a switcfi which is adapted to make connection with a source of electrical energy, as indicated by the power line A-B. A wire 51 connects one pole of switch to one side of the motor M which drives the projecting mechanism 0 the motion picture projector, and a wire 52 connects the other side-of motor M to one side of a switch 53, which forms a part of a switch unit 54, while a wire 55 connects the other side of switch 53 to the opposite pole of switch 50, thus completing-the motor circuit.

One part of switch 53 is mounted on base 56 of switch unit 54 while its other art is carried by an armature 57 hi to a bracket on base 56. Switch 53 is held in closed position by a magnet58 a ainst the action of a sprin 59. 7 One part 0 a switch 60 is mounted on ase 56 while its other part is carried by a lever 61 hinged to a bracket on base 56; switch 60 being held in closed position by a spring 62. Motor M drives the projecting mechanism of the projector belts 63 and 64 which support rollers ably mounted on a lever 67 hinged above lever 61 and carrying anarm 68 which is adapted to swing the end of lever 61 downwardly and open switch 60 if belt 63 should break and allow roller to fall. If belt 64 should break, roller 66 would fall upon the end of lever 61 and open switch 60.

A wire 69 connects one side of switch 60 to wire 51 and a wire 70 connects its other side to one end of the winding of electro-ma et 58. A. wire 71 connects the other end 0 the winding of magnet 58 to one terminal of mer-' cury switch 16 while the other terminal of mercury switch 16 is connected to wire-55 by means of a wire 72. It is thus evident that, as

rent ma flow throughmagnet 58 and allow it to ho (1 switch 53 in closed position.

One end of the'primary winding of a transformer 73 is connected by 'a wire 74 to wire 51 and its other end connected by a wire .75 to wire 52 so that current will flow through the primary of transformer 73 whenever switch 53 is closed. One end of the secondary winding of transformer 73 is connected by a wire 76 to one end of the winding of electro-magnet 15 and the other end of thewinding of this magnet is connected by a wire 77 to one side of switchesf78 and .79 which are normally open and adapted to be closed by the brea sides of these switchesare connected to-t'he other end of the secondary winding of transformer 73 by means of a wire 80. It will thus seen that, if either switch 78 or 79 is closed wire 55 ing of the film. The other by the breaking of the film, the current set up by transformer 73 will pass through magnet 15, energize same and cause it to attract armature 23 and trip latch 21, thus causi dowser 20 to fall and intercept the rays 2)? l1 ht passing through the film. As dowser Late 20 falls, cam 8 is rotated and spring aring 17 tilts mercury switch 16 so as to interrupt the flow of current therethrou h, thus deenergizing ma et '58 and allowing spring motor.

One end of the winding of the magnet. in attachment 24 is connected wire 80 intermediate switch 78 and transformer 3, while the other end of its windmg is connected by a wire 82 to wire 76 so thatthe current set up by transformer 73 will flow through this magnet and energize it. If the attachment shown in Figure 1 is employed, plunger 28 will be held in its 11 per, or inoperative, position by the power 0 magnet 26. Should switch 53 be opened,

the flow of current through the primary of transformer 73 will be interrupted and consequently no current will be set up by its byawire 81 to 5 59 to open switch 53 and stop the secondary and magnet 26 willbe deenergized,

thus allowing plunger 28to 38 against trip arm 22 and'actuate safety evice 9.

If either of the attachments shown in Figures 4 or 6 is employed, the current set up by transformer 73 will energize magnet 41 or 41' 45 against the switch 53 be deenergized, 45 upwardly and cause it to hold armature action of spring 46; Should opened and magnet 41 or 41 spring 46 will swing armature fall, swing lever and raise trip arm 22, thus actuating safety device 9.

Assuming that the projecting machine is in condition for operation and switch 50 closed, through for the ary which flows through wire 80,- wire 81,.the electro-magnet in attachment 24, wire 82 and wire 76, to the transformer; thus keeping the electro magnet energized and preventing trip arm 22 from being raised but, if switch 53 should be opened by the breaking of a belt or failure of power to the motor, this flow of current would be interrupted and the mag net deenergized, causing. the actuation of device 9. I i

Current flows from switch 50 through wire 51, wire 69, switch 60, wire 70, electromagnet 58, wire 71, mercury switch 16, wire 72 and wire 55 to switch 50, thus energizing magnet current will flow from switch 50 wire 51, motor M, wire 52, switch 53, to switch 50, thus providing power motor and causing the projector to be operated. 'At the same time, current will flow .58 so that 'it holds armature 57 against the action of spring 59 and allows switch 53 to remain closed. If belt 63 or belt 64 should break or the supply of electrical energy fail, magnet 58 will be deenergized and switch 53 opened, thus stopping the motor, deenergizing the magnet in attachment 24 and actuating safety device 9.

If a film should break, either above or below the aperture plate, switch 78 or switch 79 will be closed by suitable means on the projector and not shown and thus will complete the electrical circuit and current will flow froni one end of the secondary winding of transformer 73 through wire 80, switch 78 or 79, wire '17, electro-magnet 15, wire 76, to the other end of the secondary winding, thus energizing magnet and causing it to attract armature 23 and trip latch 21 which allows dowserto fall and rotate cam 18 and cause spring bearing 17 to tilt mercury switch 16 forwardly and open the circuit at this point which will cause magnet 58 to be deenergized and allow spring 59 to open switch 53.

With an apparatus arranged and electrically connected as above described, the rays of light passing through a fihn will be intercepted and the motor stopped in case anyi thing should happen to the film such as breaking, tearing, or clogging, or should the projecting mechanism cease to function from any cause, such as the breaking of a belt or the failure of power.

Of course, the safety devices herein illustrated may be modified and changed in various ways without de arting from the invention herein set orth and hereafter claimed.

I claim:

1. Fire prevention apparatus for a motor driven projecting machine comprising a safety device having a dowser, a magnet in said device adapted to be energized when the film breaks, tears, clogs, etc., a trip arm for holding the dowser out of light obstructing position when the magnet is deenergized and for permitting the closing of said dowser when the magnet is energized, a make and break switch for maintaining the motor circuit when the dowser is raised out of light obstructing position, an auxiliary magnet associated with said safety device and normally energized when the dowser is out of light obstructing position, an armature for said auxiliary magnet, means associated with said armature for operating the trip arm to release the dowser upon the deenergization of said auxiliary magnet, a switch in the circuit of said auxiliary magnet, and a switch arm adapted to be pressed downward when a mo- 69 tor belt breaks to thereby open the last named switch to deenergize said auxiliary magnet and release said armature to thereby operate said trip arm and release said dowser.

2. Fire prevention ap aratus for a motor M driven projecting mac ine comprising a safety device having a dowser, a ma et in said device adapted to be energized w en the film breaks, tears, clogs, etc., a trip arm for holding the dowser out of 11 ht obstructin position when the ma et is eener 'zed an for permitting the c osing of sai dowser when the magnet is energized, a make and break switch for maintaining the motor circuit when the dowser is raised out of light obstructin position, an auxiliary magnet associated with said safet device and normally energized when the owser is out of light obstructing position, an armature for said auxiliary magnet, means associated with said armature for operating the trip arm to release the dowser upon the deenergization of said auxiliary magnet, a switch in the circuit of said auxiliary magnet, a switch arm adapted to be pressed downward when a motor belt breaks to thereby open the last named switch to deenergize said auxiliary magnet and release said armature to thereby operate said trip arm and release 'said dowser, and means operated by the falling dowser to tilt said first named switch for opening said mo-v tor circuit.

3. Fire prevention ap aratus for a motor driven projectin mac iine comprising a safety device hav ng a dowser, a magnet in said device adapted to be energized when the film breaks, tears, clogs, etc., a trip arm for holding the dowser out of ii ht obstructing position when the magnet is eenergized and for permitting the closing of said dowser when the magnet is energized, a tiltably mounted mercury switch for maintaining the motor circuit when the dowser is raised out of light obstructing position, an auxiliary magnet associated with said safety device and normally energized when the dowser is out of light obstructing position, an armature for said auxiliary magnet, means associated with said armature for operating the trip arm to release the dowser upon the deenergization of said auxiliarymagnet, a switch in the circuit of said auxiliary magnet, a switch arm adapted to be pressed downward when a motor belt breaks to thereby open the last named switch to deenergize said auxiliary magnet and release said armature to thereby operate said trip arm and release said dowser, and means operated by the falling dowser to tilt said mercury switch for opening said motor circuit.

4. Fire prevention ap driven projecting mac safety device having a dowser, a magnet in said device adapted to be energized when the film breaks, tears, clogs, etc., a trip arm for holding the dowser out of light obstructing position when the magnet is deenergized and for permitting the closing of said dowser when the magnet is energized, a make and aratus for a motor break switch for maintaining the motor circuit when the dowser is raised out of light ine comprising a obstructing position, an auxiliary magnet associated with said safety device and normal] energized when the dowser is out of light ob-' structing position, an armature for said auxiliary magnet, a lever pivotally mounted and having its one end engaging the armature and its other end en aging the trip arm, means associated wit said armature for operating the trip arm to release the dowser 10 upon the deenergization of said auxiliary magnet, a switch in the circuit of said auxiliary magnet, and a switch arm adapted to be pressed downward when a motor belt breaks to thereby open the last named switch to de- 15 energize said auxiliary magnet and release said armature to thereby operate said trip arm through the medium of said pivoted lever to release said dowser. In testimony whereof I have signed my 2 name to this s ecification.

OSEPH ELLIS COHEN. 

